Sound Advice

Can you get the right answer if you ask the wrong question?

Common sense would dictate that asking how to get to the beach would seldom get you directions to the mountains. Likewise, trying to solve the problem of Noise Induced Hearing Loss (NIHL) by fixing how people choose and put in their hearing protection might be only part of the answer.

Noise Induced Hearing Loss (NIHL) is still a concern.

Noise Induced Hearing Loss affects, by some reports, 1/3 of the persons in North America working in noise. If 1/3 of the people in New York City had the same malady, you can bet the Centers for Disease Control and Prevention (CDC) would respond. Likewise, the National Institute of Occupational Safety & Health, the CDC’s workplace health and safety arm, has been on the case of NIHL for decades. Regrettably, it is still a real problem.

In the last five years, several products have come on the market designed to measure the attenuation hearing protectors give to the people wearing them. These are portable systems to measure the attenuation real people get in their work settings as opposed to measurements in a laboratory. The granddaddy of these systems, FitCheck, has been around since 1994 and has been used extensively by companies like Alcoa to measure how effective their workers are at selecting and inserting effective hearing protection. The problem these systems are trying to resolve is: How do we marry the right hearing protector with an individual and teach him or her to get the attenuation needed for it”

Certainly this is a worthwhile goal provided once the protector is fit, it stays in their ears. Aye, but there’s the rub. Dr. Peter Rabinovitch has studied Alcoa’s hearing conservation program for many years. Dr. Rabinovitch says that “he can see no outcomes in Alcoa’s hearing conservation program attributable to the use of Fit Checking systems”. That’s a lot of teaching and testing for no improvement in reducing NIHL.

Dr. Barry Bessler, in a speech to the National Hearing Conservation Association in 2007 tried to explain why rational, intelligent, normal people would turn up their digital music players loud enough to hurt their ears. Dr. Bessler’s answer was reasoned and complex. One of the points he made is relevant to this conversation. He theorized that our sense of hearing is “hard wired” to our sense of safety. Impair hearing and we don’t feel safe. In wanting to keep “in touch” with our environment, to feel safe, we need to be able to hear. Therefore, if we are using hearing protection it must not block our ability to hear. It must just make it safe to do so. Given that most types of hearing protection substantially reduce our ability to hear our environment, will workers keep these protectors in their ears? The evidence seems to indicate that they won’t.

This brings me back to my original point, in developing systems/machines to measure attenuation are we solving the problem of NIHL. So what we need to do is not worry about how much noise reduction a properly-worn hearing protector may provide if inserted in total compliance with the manufactuer’s instruction. What we need to worry about is whether the protector is providing sufficient noise reduction for the noise in which the wearer works. Instead of using these systems/machines to teach, we should be using them to verify.

FOR EXAMPLE
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If Joe is is carrying a noise burden of 92 dBA and he needs only 17 dB of noise reduction to be safe and can get a consistent 17 dB of noise reduction from an earplug with an NRR of 33 dB, GOOD! Joe doesn’t have to be taught how to get 33 dB of noise reduction. Or, in the case of a custom earplug, one should be made for Joe that givens him 17 dB of noise reduction.

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I’m afraid I have my doubts that such a direction will be taken. We need to be talking about making hearing protection as invisible to hearing as safety glasses are to vision. Instead, we have made them as cumbersome as full-face respirators.

Custom Protect Ear has been providing custom hearing devices for over 25 years. The custom molded ear products sometimes called Personalized Hearing Protection, are just as, if not more, effective for the prevention of noise-induced hearing loss as are disposable earplugs.

What is a custom-moulded earplug?

A custom-moulded earplug is a laboratory-made earplug made from moulds taken by trained experienced impression takers. In North America the experienced impression takers may be audiologists, licensed hearing aid dispensers, or impression takers well trained by the manufacture. Most often, these are made of acrylic or soft silicone that can fit the ear and the ear canal tightly. The advantage of the softer earplugs is they change shape slightly as the wearer’s ear canal changes shape when talking or chewing, thereby continuing to seal during those activities.This deems to have great benefits when working in high activity – noise induced environments.

The custom-moulded earplugs are typically delivered in a protective storage/carrying pouch and will be accompanied with a tube of lubricant (most often petroleum jelly).

The lubricant is applied to the earplugs during their initial use/break in period. The lubricant makes the earplugs easier to insert and also softens the interface of the earplug and ear improving comfort.

After about ten or so uses with the lubricant applications can stop as the silicon should have absorbed enough material to be easily inserted for the life of the earplug.

What is a disposable earplug?

So-called “foam” and pre-moulded earplugs are designed to be used for one time or in some cases, a few times. Exceptions to this restriction are those very expensive earplugs such as the Hi-Fi or military earplug that can be cleaned for repeated use.

Until the 1970’s the most common earplug was the V51-R made from soft silicone, a single-flange earplug developed for the military that came in five sizes. Because it didn’t work well, it required precise fitting. Eventually it was discontinued due to repeated pressures from the scientists and practitioners in the hearing health community. Later other earplugs were developed with multiple flanges.

When is a “custom-moulded” earplug NOT “custom”, but really a long-term use disposable earplug?

Simply put: Earplugs directly made from the impression materials, which can be considered as fitter-formed or mould-in-place, are not custom-moulded earplugs (Lake, 2012). This is true for a variety of reasons.

First and foremost is the impression material.Impression materials now used for laboratory-made custom-moulded earplugs are designed for the purpose of taking the impression and holding shape whist in transit to and whilst being processed to make moulds by the laboratory. Fitter-formed impression material is intended to become the final product and so it “cures” while setting during the impression process. In order for this to work, the fitter-formed impression material is more viscous than impression materials used for laboratory-made custom-moulded earplugs. As such, the likelihood of an impression free from flaws and with a faithful rendering of the shape of the concha and helix as well as the pinna and ear canal is small.

The impression for the laboratory-made custom-moulded earplug is also usually a silicone product made from mixing a base putty with a liquid or gel activator. Some laboratories use two-part silicone materials that combine catalyst and silicone in 50/50 proportion. The result is far less viscous material than used for the fitter-formed products; its viscosity is such that it may be put into a syringe for injecting into the ear canal and concha and helix of the pinna.

Second is the impression process.Fitter-formed products use putty created from combining a base putty with a liquid activator and then folding them until blended. That putty begins to cure immediately but has less-than a three-minute time window when it will be malleable. The putty is rolled into a cylinder and the pushed down the ear canal and padded into the concha and helix of the pinna. Once it seems to have cured, it is removed from the ear and trimmed. Handles or the ends of cords may have been attached after the insertion but before the impression cured.

For a custom-moulded laboratory-made earplug, following otoscopy, a cotton or foam dam is placed into the ear canal with its placement confirmed by otoscopy so that there is no chance for the impression material to travel deeply enough to make contact with the eardrum. As well, if the ear canal has excessive cerumin, the ear canal may be cleaned by the audiologist taking the impression or the person may be referred to his or her own physician to have the ear canals evaluated and cleaned – the exact procedure depends on locality and regulatory requirements.

Then, the impression material is injected to fill the entire ear canal between the dam and the opening of the canal behind the tragus and finally the bowl of the concha and the helix are filled. There is a debate over whether the mouth should be closed, opened, or slightly opened during the time it takes for the impression material to set. The mouth slightly open (relaxed or with a bite block of 20 mm or so that) has been shown to provide better bass than mouth closed when the earplug is modified to be used with insert earphones. There have been no published studies of the differences in noise reduction between laboratory-made custom-moulded earplugs made from mouth-relaxed versus mouth-closed impressions.

Once the impression material has set, it is carefully removed from the ear, inspected to make sure there are no creases, ridges, or other malformations, and put into a package to be sent to the laboratory. There is no trimming done by the impression taker.

The experience and training of the impression taker is also very important. Depending upon locality and professional licensing regulations, the impression taker may have been trained by the laboratory making the custom-moulded earplugs, or have academic or clinical training in impression taking. In any case, once the impression reaches the laboratory, its staff can determine the quality of the impression and may ask for a second impression if the first has flaws that the laboratory can’t adjust.

Already in the hands of some audiologists are laser scanners that can make a digital image of the impression, and the image goes to the laboratory for further processing to make the mould from which the earplug is made. As the image is stored digitally, so long as the file is not corrupted, it is possible to make as many earplugs from one impression as necessary for as long as is necessary. Soon to come will be digital imaging of the ear canal and pinna, so that there will be no use of impression material, as the image of the ear will be sent to the laboratory to be process into an earplug. Either of these techniques should remove impression making from the hands of amateurs and DIY’ers.

What dB Blocker wearers are saying.

“I would like to say thanks I have had my db blocker vented convertible ear plugs for the past 7 years I would like to say that you guys make the best ear plugs I have come across I am a welder I have bin in the industry for the past 10 years. That are worth every penny great quality. Thanks you so much I will be going to my boss’s at my work (national steel car) to get all my brothers a pair of Db blockers.”

Custom Molded Vs. Disposable Earplugs

Custom-moulded earplugs, sometimes called Personalized Hearing Protection, are just as, if not more, effective for the prevention of noise-induced hearing loss as are disposable earplugs. There have not been head-to-head studies of the relative effectiveness, but two major long-term retrospective studies of the effectiveness of hearing loss prevention programs can provide insight. Read Complete Whitepaper by Dr. John Franks.

Choose Custom-Moulded Over Disposable Earplugs Abstract

In 1989 Franks, Davis and Krieg (Franks, 1989) reported that noise-exposed employees of a company that provided custom earplugs to all of its employees had changes in hearing over a ten-year period that were no different from their non-noise-exposed colleagues and peers. The company had six facilities around the United States with noise-exposed employees as well as a cadre of employees of similar age and gender who were not exposed to workplace noise. All of the employees studied had been with the company for the ten-year period studied. Audiometric, health and hobby histories, as well as noise-exposure levels were known for all employees. A ten-year segment of the records was used for the analysis.

It was company policy to provide custom earplugs for use at work or home as well as to provide disposable earplugs to employees to use outside of work. Analysis of the data revealed that the changes in hearing that were observed were not due to exposure to workplace noise. Having resolved that and adjusting for age, statistical analysis showed hypertension and diabetes increased the propensity to have worsening hearing for women. For men, the factors were hypertension, diabetes, and use of firearms.

In 2011, Heyer, et al. (Heyer N, 2011- view abstract) reported a retrospective analysis of hearing conservation programs for three different companies, all of which relied upon premoulded or slow-recovery foam disposable earplugs to protect employees from noise-induced hearing loss.

> Company 1 made automobile body components,

> Company 2 made automotive parts,

> Company 3 was a major food processing company.

All of the employees had been at the study sites for longer than the period of time studied. Noise-exposure and hearing protector use histories were established for each employee as were audiometric records including relevant medical and hobby histories. In this study there was not a cohort of fellow non-noise-exposed employees, so the outcome was compared to a standardized set of data (American National Standards Institute, S3.44-1996 (R 2006)). The noise-exposure levels in the three companies studied were similar, as were they to the noise-exposure levels in the Franks, et al. (1989) study. Heyer, et al. found that two factors were associated with changes in hearing: age and noise-exposure level. Because of the strong effects age and noise-exposure level had on the data, it was not possible to assess the influence of other factors.

Had the pre-moulded disposable earplugs been used as effectively as the custom-moulded earplugs, then noise-exposure level should not have been a main effect associated with changes in hearing; with age factored out, noise-exposure level was as much a primary risk as would be expected for the unprotected.

Music Induced Hearing Loss (MIHL)

From Eric Clapton to Pete Townsend, the music industry – especially rock music – has several notable musicians who suffer from Music Induced Hearing loss (MIHL).

The only thing worse than enjoying live music and then suddenly cringing in pain from feedback squeals is NOT hearing them. Sitting near a large stack of speakers can leave your ears dull for many hours after a show.

For anyone who has attended a music venue and left with ringing in their ears or muffled hearing afterward, it is no surprise that the noise level at concerts can cause damage. The average decibel (db) level at a rock concert is +110dbs, which is loud enough to cause permanent damage after just 15 minutes.

What Do Musicians Ear Plugs Do?

Unlike industrial noise exposure, there are many sources of hearing trauma in the musical venue. From the previously mentioned feedback and sound checks, to unexpected blasts from speakers, to limiters that are not set correctly, concerts are a veritable landmine of dangerous noise levels. If you work in the music industry, it should be obvious that you need to protect your hearing, but even music enthusiasts or musicians who simply enjoy regular concerts also should consider musicians earplugs as protection at every concert.

At Custom Protect Ear, we have a commitment to our customers to give them the highest quality ear protection available. Our dB Blocker™ hearing protectors are custom fit to each individual for the maximum comfort and the clarity to hear others without having to remove the earplug. This is particularly important for those in the music industry where one needs to protect the ears yet still hear and enjoy music.

dB Blocker™ Sweet Tones Musicians Earpieces

Our dB Blocker™ Sweet Tones Musicians earpieces are designed for musicians who want to hear sound without distortion but with less volume. If you are also concerned about hearing damage caused by regular use of earphones, we have your solution.

Love to Listen to Music with Ear Buds?

Custom Protect Ear can also pair up your high quality earphones or cell phone headset with a dB Blocker™ earpiece for a comfortable, slip-free fit that protects your hearing and eliminates background noise. A perfect fit for your music enjoyment!

I was recently perusing the ISHN Facebook fan page and saw this article posted. It is a very interesting article, something definitely worth sharing since one of the most forgotten senses is hearing. As individuals we tend to take our hearing for granted, until it is too late. In a noisy world full of sound devices, traffic & construction, congestion and especially noise in our workplaces it is important to be cognoscente of the potential harm we could be doing to our hearing. enjoy the read. Hearing Protection

Hearing loss is the most commonly recorded occupational illness in manufacturing, accounting for 1 in 9 recordable illnesses. The reasons behind these staggering numbers are obvious, with all the large and loud machinery in this line of business. And this problem is all over the nation. Manufacturing is one of the largest industries in the U.S., which means hearing loss can spread rapidly. In fact, a study in Michigan reveals that more than half of all cases of permanent workplace hearing loss is caused by the manufacturing sector. Learn about Personalized Hearing Protection for Manufacturing Companies.

Hearing Loss in Construction, Carpentry and Mining

Whether outside your window, on your walk to work or anywhere else on the street, you may be painfully familiar with the extreme noise levels of construction sites. Now imagine working there. For the country’s construction workers, these sounds can be particularly hazardous to hearing health. Long periods of exposure to noise over 85dB is considered dangerous to one’s hearing, yet many of the most common construction tools make noise well above this cautionary value. Let’s consider one the noisiest yet most common construction tools: the hammer drill. This ear-shattering tool registers at nearly 115dB. With these dangerous decibels, whether you are performing construction work at home or for pay, make sure to wear the right kind of ear protection. Learn more about the Industry. Now Available: SMART MUFFS for double hearing protection

Miners and carpenters are particularly affected due to a similarly noisy tool set, as the next couple of graphs can attest.

Traveling on a motorbike beyond 50mph, can expose the driver to up to 90dB of noise under the helmet. The maximum recommended exposure limit at this level is 2.5-3 hours at a time. While slow city traffic might be more manageable, it’s more the day-in/day-out exposure, as well as longer travels on open roads that do the damage. Courier or no courier, all bikers can be affected.Learn how bikers can protect their hearing.

Hearing Loss in Entertainment and Nightlife

All that hubbub can hurt your ears. Loud music is one of the most common causes of hearing loss. Employees at bars, nightclubs, or concert hallsmight be enduring dangerous sound levels every night of the week.Most nightlife hotspots operate at levels well above 100 dB, which means the mood music may be doing some mega damage. Bartenders, performers, and security should all be well aware of these dangers, and seek out special earplugs specifically made for musicians. This also goes for rock stars. There are available hearing protection for individuals and musicians.

If you have ever taken a look at an airport runway, you may notice the brightly colored ear protection worn by airport traffic directors. These are not just a fashion statement, but indeed a necessary precaution. The sound of a jet engine is one of the loudest auditory occupational hazards, with sound levels at a shocking 140dB. Sound waves are invisible, but at this level, they pack a whopping force. You can find the appropriate hearing protection for Airport and Security staff.

Guns and other firearms are loud, ask any military veteran. Shooting range marshals, if not carefully protected with heavy duty on-ear protectors or custom made ear plugs, can be exposed to up to 140dB of noise exposure during any given day. One more reason to think twice about that next excursion to the shooting range or hunting trip.

2010 was tough year for workers in noise in both the U.S. and Canada. First the EPA tried to address problems with the labeling of hearing protectors. What problems? Well, currently the label on a hearing protector tells workers of the potential hearing protection that could be obtained from a protector. The problem is that few achieve this level outside of the laboratory. The problem is so acute that OSHA (Occupational Safety and Health Administration) insists companies de-rate hearing protection (by a lot) when calculating how much protection they need to give a worker. This de-rating lowers the protection value of a hearing protector with a lab rating of 30 to 11.5. – over 60%.

So the EPA asked the ANSI working group on hearing protection for a better way to rate hearing protection while still measuring the “potential” of the protector. The new rule will provide 2 numbers for rating hearing protection. The lower of these 2 numbers will be higher than the number used today (meaning further away from what happens in the real world – back to the drawing board).

OSHA announced yesterday that it is withdrawing its proposed noise interpretation that originally appeared in the Federal Register on October 19, 2010. OSHA had planned to insist companies with noise levels above 90 dB, engineer out the noise because hearing conservation programs are not working. They point to the fact that since 2004, 125,000 workers have had permanent damage to their hearing. OSHA, after meeting with Senators Leiberman and Snowe, of the Senate Committee on Small Business and Entrepreneurship Sens. Snowe and Lieberman are also co-chairs of the Senate Task Force on Manufacturing. Canadian regulations tend to follow the U.S. as these economies are closely linked.

So hearing protection labels are more misleading and no one will have to reduce the noise their factories make. It was a tough year for workers in noise. Better toughen up your ears.